Pregnancy Calculator – Track Your Week, Trimester & Due Date
Instantly track your pregnancy progress. Our calculator analyzes your Last Menstrual Period (LMP), Conception Date, or Ultrasound Date to reveal your exact gestational age, current trimester, and baby's developmental milestones.
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IVF & Ultrasound Support
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How to Use the Pregnancy Calculator
Whether you know your last period, conception date, or have an ultrasound, our tool instantly gives you precise gestational data. Here is how to use it:
1
Select Method
Choose between LMP, Due Date, Conception, Ultrasound, or IVF for the most accurate baseline.
2
Enter Date
Input your specific date. Our algorithm uses Naegele's rule and standard clinical formulas to map your timeline.
3
Get Results
Instantly discover your current week, trimester, estimated due date, and fetal development milestones.
Understanding Pregnancy Weeks & Trimesters
Pregnancy is measured in weeks and days rather than months because fetal development occurs rapidly. A standard pregnancy lasts about 40 weeks, starting from the first day of your last menstrual period (LMP).
First Trimester (Weeks 1-13)The foundational stage where major organs and body systems form. The embryo implants, and a heartbeat is detected.
Second Trimester (Weeks 14-27)Often called the "honeymoon phase." Baby undergoes rapid growth, you feel first movements, and anatomy is detailed.
Third Trimester (Weeks 28-40+)The final stretch focusing on weight gain and lung maturity, preparing for the birthing process.
Calculation Methods Explained
There are several ways medical professionals date a pregnancy. Our calculator supports the most proven methodologies:
LMP & Conception
LMP: Assumes a standard 28-day cycle, adding 280 days to the first day of your last period (Naegele's Rule).
Conception: For those tracking ovulation. Adds 266 days to the known conception date.
Clinical Methods
Ultrasound: The medical gold standard. Measures Crown-Rump Length (CRL) in early scans to accurately date the pregnancy.
IVF: Calculated with high precision based on embryo transfer date (Day 3 or Day 5).
Frequently Asked Questions
How does the pregnancy calculator work?
The pregnancy calculator estimates your current week, trimester, and baby's growth based on your due date, last menstrual period, or conception date. It assumes a standard 40-week gestation.
How many weeks are there in a pregnancy?
A standard full-term pregnancy lasts about 40 weeks, which translates to roughly 9 months. Babies born between 37 and 42 weeks are generally considered full term.
What are the three trimesters of pregnancy?
The first trimester covers weeks 1 through 13, the second is weeks 14 through 27, and the third trimester is from week 28 up to week 40 or birth.
Can this calculator estimate my conception date?
Yes. By entering your due date or LMP, the calculator can estimate your likely conception date, which typically occurs about two weeks after your last period.
What information does the pregnancy calculator provide?
It provides your current pregnancy week and exact day, your current trimester, your baby’s estimated length and weight, conception date, and a percentage of progress toward your due date.
Is this pregnancy calculator accurate?
It is highly accurate based on standard clinical algorithms. However, every pregnancy is unique, and early ultrasound measurements by a doctor are the most precise way to date a pregnancy.
How is my due date calculated using my last menstrual period (LMP)?
Most healthcare providers calculate your due date by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP).
What is Naegele's rule?
Naegele's rule is a standard way of calculating the due date. You take the first day of your last menstrual period, add seven days, and subtract three months.
Can my due date change after my first ultrasound?
Yes. Early ultrasounds, usually performed in the first trimester, measure the baby's crown-to-rump length and are considered the most accurate method for establishing a due date.
How do I calculate my due date if I have irregular periods?
If you have irregular periods, the LMP method might not be accurate. It's best to consult your doctor, who will likely recommend a dating ultrasound.
How does IVF affect my due date calculation?
For IVF pregnancies, the due date is calculated based on your embryo transfer date and the age of the embryo (typically 3-day or 5-day) rather than your last period.
Why is my pregnancy measured in weeks instead of months?
Fetal development occurs rapidly, with significant changes happening every few days. Measuring by weeks provides a much more precise and medically useful timeline.
What is considered a full-term pregnancy?
A pregnancy is considered early term between 37 and 38 weeks, full term between 39 and 40 weeks, and late term at 41 weeks.
When will I start feeling my baby move (quickening)?
Most first-time mothers begin to feel their baby move between 18 and 22 weeks of pregnancy. Experienced mothers might feel it a bit earlier.
How much weight should I gain during my pregnancy?
Weight gain recommendations vary based on your pre-pregnancy BMI. For someone with a normal BMI, the typical recommendation is between 25 and 35 pounds, but always consult your doctor.
Educational & Medical DisclaimerThis calculator and its accompanying information are for educational purposes only. It is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition, diet, or fitness regimen.